NXP Semiconductors TDA3681J/N2S,112

Overview

TDA3681J/N2S,112 from NXP Semiconductors (formerly Philips) is a 4-output automotive voltage regulator IC with integrated power switch and ignition buffer, designed for car radio systems. It delivers regulated outputs of 8.5 V/600 mA (REG1), 5.0 V/300 mA (REG2), 5.0 V/1400 mA (REG3), and 3.3 V/1 A (REG4), operates across −18 V to +50 V supply range, and includes load dump protection up to 50 V for 50 ms.

For engineers reviewing the TDA3681J/N2S,112 datasheet, TDA3681J/N2S,112 pinout, TDA3681J/N2S,112 application, or TDA3681J/N2S,112 equivalent, this page provides verified functional specifications, validated pin roles, confirmed automotive-grade protections (reverse polarity, thermal shutdown, foldback current limiting), and real-world use context in microcontroller-supplied infotainment systems.

Technical Context

The TDA3681J/N2S,112 integrates four independent linear regulators with foldback current protection, a protected high-current power switch (3 A peak, 1.8 A continuous), and a Schmitt-triggered ignition buffer with push-pull output. Regulators 1, 3, and 4 are VP1/VP2-controlled and feature combined enable (EN1/3) and separate enable (EN4, ENSW), while REG2 remains active during load dump and thermal shutdown.

Its hold output (open-collector, active LOW) aggregates fault conditions-including low VP1, out-of-regulation on any switchable regulator, temperature overthreshold (>150 °C), and load dump-via internal OR logic. The reset output (push-pull, active LOW) provides adjustable delay via external capacitor CRES (e.g., 47 nF yields 20–70 ms delay) to ensure controlled microcontroller startup.

Key Specifications

Pinout & Package

Package: DBS17P - plastic DIL-bent-SIL power package, 17-lead, lead length 7.7 mm (SOT243-3). Heat tab internally connected to GND (pin 13).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multiple-output automotive regulator applications.

Compared with LM2678T-ADJ/NOPB and TPS65381A-Q1, the TDA3681J/N2S,112 delivers purpose-built automotive power management with zero-software fault coordination, hardware-enforced hold/reset timing, and ignition-native interface - reducing design validation effort for cost-sensitive car radio platforms.

Availability

TDA3681J/N2S,112 is available at Aetrix Electronics and suitable for automotive infotainment, telematics control units, and premium audio amplifier supply requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.

Supply support for TDA3681J/N2S,112 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep heritage in automotive analog and power management ICs.

The TDA3681J/N2S,112 belongs to NXP's legacy automotive power management portfolio, specifically engineered for cost-effective, high-reliability car radio systems requiring integrated multi-rail regulation, ignition interface, and robust transient protection without MCU intervention.

FAQ

What is the maximum continuous current capability of the power switch in TDA3681J/N2S,112?

The power switch in TDA3681J/N2S,112 delivers 1.8 A continuous current at VP1 ≤16 V and VSW = 13.5 V. At VP1 ≥17 V, it clamps output to 16 V maximum and limits continuous current to 1.8 A. Peak current reaches 3 A for short durations before foldback activation, as confirmed in the Quick Reference Data and Characteristics tables.

How does the TDA3681J/N2S,112 handle load dump events, and what protection thresholds apply?

The TDA3681J/N2S,112 withstands load dump pulses up to 50 V for ≤50 ms with tr ≥2.5 ms on both VP1 and VP2 pins. During such events, REG2 remains operational, while REG1, REG3, and REG4 shut down above 18 V. The HOLD output activates immediately, signaling system-level fault. This behavior is explicitly defined in the Limiting Values and Functional Description sections.

Can TDA3681J/N2S,112 operate with only one supply voltage, or is VP2 mandatory for REG3 and REG4?

VP2 is not mandatory: REG3 and REG4 can be powered from VP1 alone. However, connecting VP2 to a lower-voltage source (≥6.5 V, e.g., a DC-DC converter) reduces power dissipation and thermal stress. The datasheet confirms VP2 is "second supply voltage" - optional but recommended for efficiency in high-current applications like REG3 (1400 mA).

What is the function of the BU (backup) pin in TDA3681J/N2S,112, and how is it used?

The BU pin provides a dedicated backup path to REG2, allowing an external capacitor (minimum 1 µF, typically 100 µF) to sustain 5 V output during VP1 dropout (e.g., engine cranking). When VP1 falls below regulation, BU supplies REG2 directly, enabling the MCU to execute controlled shutdown or maintain critical functions for up to 100+ ms depending on capacitor size and load.

Is the reset delay time of TDA3681J/N2S,112 programmable, and how is it calculated?

Yes, the reset delay time of TDA3681J/N2S,112 is programmable via external capacitor CRES. With CRES = 47 nF, delay ranges from 20–70 ms (typ. 35 ms). The formula td(RES) = (C × 750 × 10³) / Ich applies, where Ich = 4 µA typical charge current. This delay ensures MCU reset release only after all regulators stabilize, preventing uncontrolled startup.